Data processing system

ABSTRACT

An image processing unit decodes coded data that have been coded and synthesizes the decoded moving image with graphics data. In a case where only graphics data are to be displayed, a bypass unit outputs the graphics data to a display device without use of an image processing unit. A control unit performs control of the supplying of a power supply voltage and a clock to a region containing the image processing unit and control of the bypass unit. If processing at the image processing unit is unnecessary, the supply of power supply voltage or the supply of clock to the region containing the image processing unit is stopped to stop the region and enable reduction of wasteful power consumption.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention concerns a data processing system comprising a plurality of data processing units that operate independent of each other.

[0003] 2. Description of the Related Art

[0004] Examples of a data processing system, comprising a plurality of data processing units that operate independent of each other, include portable terminals, such as portable phones that are enabled to perform moving image communication.

[0005] With progresses in the furnishing of high-speed communication infrastructure for third-generation mobile communication, etc. in recent years, the transmittable amount of information has increased significantly and moving image communication has become possible.

[0006] In accompaniment, the display functions of a portable terminal, such as a portable telephone, etc., are changing from those that are mainly for graphics display, such as display of the time, menus, remaining battery quantity, etc. to those for moving image displays, such as synthesized images of moving images and graphics, etc.

[0007] Generally, an enormous amount of data is processed in the data processing of a moving image. Thus when all processes, including moving image processes, are to be performed by a single data processing unit, such as a general-purpose processor, etc., the data processing unit is required to exhibit extremely high performance.

[0008] Thus in many cases, a data processing unit that satisfies the required performance does not exist or the realization of a data processing unit that satisfies the required performance is difficult.

[0009] Conventional portable terminals are thus equipped with a separate data processing unit or LSI that is dedicated to moving image processing.

[0010] As prior-art examples, an arrangement of a display system of a portable terminal that performs only graphics display is shown in FIG. 6 and an arrangement of a display system of a portable terminal that is enabled to perform moving image communication is shown in FIG. 7.

[0011] Presently for moving image communication by a portable terminal, MPEG-4, which is an international standard for high-efficiency moving image coding, is most likely to be used.

[0012] In many cases, a MPEG-4 moving image data processing unit is equipped with on-screen display (OSD) functions for handling graphics, functions for synthesizing moving image data and graphics data, and functions for outputting image data to a display data processing unit.

[0013] Prior-art portable terminal display systems shall now be described in outline using FIGS. 6 and 7.

[0014] As shown in FIG. 6, a display system that performs only graphics display comprises, in outline, a CPU 302, a display device 303, a voltage regulating device 311, and a clock generating device 312.

[0015] CPU 302 generates graphics data to be displayed. Display device 303 displays the graphics data output from CPU 302.

[0016] Voltage regulating device 311 supplies optimal power supply voltages from system power supply 324 to CPU 302 and display device 303. Clock generating device 312 supplies clocks to CPU 302 and display device 303.

[0017] CPU 302 operates by a power supply voltage 325, supplied from voltage regulating device 311, and a clock 329, supplied from clock generating device 312.

[0018] Display device 303 operates by a power supply voltage 328, supplied from voltage regulating device 311, and a clock 332, supplied from clock generating device 312.

[0019] The flow of the processes of the display system of FIG. 6 shall now be described.

[0020] The graphics data to be displayed by display device 303 is output as output data 314 from CPU 302 to display device 303.

[0021] The graphics data that are output are graphics data concerning menu display, time display, etc.

[0022] These graphics data are input directly as an external input 313.

[0023] Or, these graphics data are stored inside CPU 302 in advance and output to and displayed by display device 303 in accordance with information input as external input 313.

[0024] As shown in FIG. 7, a portable terminal display system that can perform moving image communication comprises, in outline, an image processing LSI 401, a display device 103, a CPU 102, a voltage regulating device 111, and a clock generating device 112.

[0025] Image processing LSI 401 has the functions of decoding coded data that have been coded in accordance with the MPEG-4 coding method and synthesizing the decoded moving image with graphics data.

[0026] Display device 103 displays the display image data generated by image processing LSI 401.

[0027] CPU 102 prepares graphics data to be displayed on display device 103 and sends these data to image processing LSI 401.

[0028] Also, when a moving image is to be displayed on display device 103, CPU 102 sends the coded data of the moving image to be displayed to image processing LSI 401.

[0029] Voltage regulating device 111 supplies optimal power supply voltages from system power supply 124 to image processing LSI 401, CPU 102, and display device 103.

[0030] Clock generating device 112 supplies clocks to image processing LSI 401, CPU 102, and display device 103.

[0031] CPU 102 operates by a power supply voltage 125, supplied from voltage regulating device 111, and a clock 129, supplied from clock generating device 112.

[0032] Image processing LSI 401 operates by a power supply voltage 426, supplied from voltage regulating device 111, and a clock 430, supplied from clock generating device 112.

[0033] Display device 103 operates by a power supply voltage 128, supplied from voltage regulating device 111, and a clock 132, supplied from clock generating device 112.

[0034] The flow of the processes of the display system of FIG. 7 shall now be described.

[0035] CPU 102 outputs graphics data, concerning the time, menus, etc., as well as bit stream data, which are MPEG-4 coded data, to image processing LSI 401 as output data 414.

[0036] The graphics data and the MPEG-4 coded data, which are moving image data, output to image processing LSI 401 are input into CPU 102 as an external input 113.

[0037] Or, these data are stored in the interior of CPU 102 in advance and output in accordance with information input from external input 113.

[0038] At image processing LSI 401, the MPEG-4 coded data are decoded and reconfigured as an image at image processing unit 404.

[0039] The process of synthesizing the decoded image data and the graphics data input from CPU 102 is then performed at image processing unit 404.

[0040] The display data resulting from image synthesis are then output to display device 103 as output data 418 of image processing LSI 401.

[0041] Display device 103 performs screen display based on the display data.

[0042] However in general, even with a portable terminal that is enabled to perform moving image communication, the displays will mainly be displays besides moving images, such as time display, menu displays, etc.

[0043] In such cases, moving image data processing is not necessary and only graphics data are displayed.

[0044] Thus with a prior-art data processing system with an arrangement such as that shown in FIG. 7, only graphics data will be output from CPU 102.

[0045] And at image processing unit 404 inside image processing LSI 401, the decoding of MPEG-4 coded data and the synthesizing of a decoded image with graphics data are not performed and the graphics data are output as they are as display data to display device 103.

[0046] Though the realization of low power consumption is an important theme for battery-driven portable terminals, with the prior-art data processing system shown in FIG. 7, power and clocks are supplied to the MPEG-4 image processing parts (moving image decoding process part and synthesizing process part) inside image processing unit 404 even when only graphics data are output.

[0047] There is thus the problem in that power is consumed wastefully in the form of unnecessary power consumption by the charging and discharging of a clock line and power consumption due to leak currents in the standby state.

OBJECTS AND SUMMARY OF THE INVENTION

[0048] Thus an object of this invention is to provide a data processing system that enables reduction of wasteful power consumption.

[0049] A data processing system of a first aspect of this invention comprises at least one first data processing unit, performing preprocessing and outputting preprocessed data, at least one second data processing unit, performing data processing on the preprocessed data and outputting processing result data, at least one third data processing unit, performing postprocessing on the processing result data, a bypass unit, transferring the preprocessed data input from the first data processing unit to one of the second data processing unit and the third data processing unit, and a control unit, controlling the bypass unit, and in a case where processing of the preprocessed data by the second data processing unit is not required, the bypass unit transfers the input preprocessed data to the third data processing unit in accordance with an instruction from the control unit and in a case where processing of the preprocessed data by the second data processing unit is not required, the control unit stops the second data processing unit.

[0050] By this arrangement, wasteful power consumption, in the form of unnecessary power consumption by charging and discharging of a clock line of a specific process executing unit inside a second data processing unit and power consumption due to leak currents in the standby state, can be reduced.

[0051] Thus, for example, the battery duration of a portable terminal that employs this data processing system can be improved.

[0052] A second aspect of this invention provides a data processing system, wherein the abovementioned second data processing unit and the abovementioned bypass unit are arranged within a single integrated circuit.

[0053] By this arrangement, the system can be made small in mounting area.

[0054] A third aspect of this invention provides a data processing system, wherein the abovementioned second data processing unit, the abovementioned bypass unit, and the abovementioned control unit are arranged within a single integrated circuit.

[0055] By this arrangement, the system can be made small in mounting area.

[0056] A fourth aspect of this invention provides a data processing system, wherein the abovementioned control unit stops the supply of a clock to the abovementioned second data processing unit to stop the abovementioned second data processing unit.

[0057] A fifth aspect of this invention provides a data processing system, wherein the abovementioned control unit stops the supply of a power supply voltage to the abovementioned second data processing unit to stop the abovementioned second data processing unit.

[0058] A sixth aspect of this invention provides a data processing system, wherein the abovementioned control unit stops the supply of a clock and the supply of a power supply voltage to the abovementioned second data processing unit to stop the abovementioned second data processing unit.

[0059] A seventh aspect of this invention provides a data processing system, wherein the abovementioned first data processing unit is a processor.

[0060] An eighth aspect of this invention provides a data processing system, wherein the abovementioned first data processing unit is a data storage device.

[0061] A ninth aspect of this invention provides a data processing system, wherein the abovementioned third data processing unit is a display device.

[0062] A tenth aspect of this invention provides a data processing system, wherein the abovementioned third data processing unit is a data storage device.

[0063] The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0064]FIG. 1 is a diagram, showing the general arrangement of a data processing system of a first embodiment of this invention.

[0065]FIG. 2 is a diagram, showing the general arrangement of a first modification example of the data processing system of the first embodiment of this invention.

[0066]FIG. 3 is a diagram, showing the general arrangement of a second modification example of the data processing system of the first embodiment of this invention.

[0067]FIG. 4 is a diagram, showing the general arrangement of a data processing system of a second embodiment of this invention.

[0068]FIG. 5 is a diagram, showing the general arrangement of a data processing system of a third embodiment of this invention.

[0069]FIG. 6 is a diagram, showing a prior-art data processing system that is an example of a case where only graphics data are handled.

[0070]FIG. 7 is a diagram, showing a prior-art data processing system that is an example of a case where moving images and graphics data are handled.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071] Embodiments of this invention shall now be described with reference to the drawings.

[0072] (First Embodiment)

[0073]FIG. 1 is a block diagram, showing the arrangement of a data processing system of a first embodiment of this invention.

[0074] As shown in FIG. 1, this data processing system is equipped with an image processing LSI (large scale integrated circuit) 101, a display device 103, a general-purpose processor (CPU: central processing unit) 102, a voltage regulating device 111, a clock generating device 112, a control device 110, a power supply interrupting unit 122, and a clock interrupting unit 123.

[0075] Image processing LSI 101 comprises an image processing unit 104 and a bypass unit 105. Bypass unit 105 comprises a switch 108, a bypass line 117, and a selector 109.

[0076] Here, each of image processing LSI 101, display device 103, and CPU 102 is an example of a data processing unit. Also, control device 110 is an example of a control unit.

[0077] The operations of the abovementioned components shall now be described.

[0078] Image processing unit 104 of image processing LSI 101 decodes coded data that have been coded in accordance with the MPEG-4 coding method.

[0079] Image processing unit 104 then synthesizes the decoded moving image with graphics data.

[0080] Bypass unit 105 of image processing LSI 101 is used when graphics data are to be displayed without using image processing unit 104.

[0081] That is, bypass unit 105 outputs graphics data upon bypassing image processing unit 104.

[0082] Display device 103 receives the display image data generated at image processing LSI 101 and displays the received display image data. Display device 103 is, for example, a liquid crystal display, etc.

[0083] CPU 102 prepares graphics data to be displayed on display device 103 and sends the prepared graphics data to image processing LSI 101.

[0084] Also, when a moving image is to be displayed on display device 103, CPU 102 sends the coded data of the moving image to be displayed to image processing LSI 101.

[0085] Voltage regulating device 111 adjusts a voltage generated by a system power supply 124 to appropriate voltages and supplies these appropriate voltages as power supply voltages to image processing LSI 101, CPU 102, and display device 103.

[0086] Clock generating device 112 supplies appropriate clocks to image processing LSI 101, CPU 102, and display device 103.

[0087] CPU 102 operates by a power supply voltage 125, supplied from voltage regulating device 111, and a clock 129, supplied from clock generating device 112.

[0088] Display device 103 operates by a power supply voltage 128, supplied from voltage regulating device 111, and a clock 132, supplied from clock generating device 112.

[0089] Image processing LSI 101 is divided into the two regions of a region A1, which contains bypass unit 105, and a region B (slanted line part in the Figure), which contains image processing unit 104.

[0090] The region A1, which contains bypass unit 105, operates by a power supply voltage 126 (power supply voltage VddA), supplied from voltage regulating device 111, and a clock 130 (clock ClkA), supplied from clock generating device 112.

[0091] The region B, which contains image processing unit 104, operates by a power supply voltage 127 (power supply voltage VddB), supplied from voltage regulating device 111, and a clock 131 (clock ClkB), supplied from clock generating device 112.

[0092] Control device 110 performs control of the supplying of power supply voltage 127 (power supply voltage VddB) to region B (slanted line part in the Figure) inside image processing LSI 101, control of the supplying of clock 131 (clock ClkB) to region B, and control of bypass unit 105.

[0093] Power supply interrupting unit 122 performs interruption of a power supply voltage in accordance with a control signal 120 from control device 110.

[0094] Clock interrupting unit 123 performs interruption of a clock in accordance with a control signal 121 from control device 110.

[0095] The operations of the respective components of bypass unit 105 shall now be described.

[0096] Bypass line 117 outputs output data 114 from CPU 102 directly to display device 103.

[0097] Switch 108 switches between a path, by which the output data 114 from CPU 102 are output as input data 115 for image processing unit 104, and a path, by which the output data 114 from CPU 102 are output to bypass line 117.

[0098] Selector 109 selects between and outputs either the processing result data 116 at image processing unit 104 or the data output from bypass line 117.

[0099] Switch 108 and selector 109 are controlled by a control signal 119 from control device 110.

[0100] The data output by bypass unit 105 in accordance with this control signal 119 become the output data 118 of image processing LSI 101.

[0101] The details of the operations of the above-described data processing system shall now be described.

[0102] First, the operations that are performed when the moving image data and graphics data that have been output from CPU 102 are synthesized at image processing LSI 101 and the synthesized image is displayed on display device 103, that is, the image display operations that are performed when moving image communication is carried out shall be described.

[0103] First, CPU 102 prepares the graphics data to be displayed on display device 103 and the moving image coded data that have been coded in accordance with the MPEG-4 coding method.

[0104] CPU 102 then outputs the prepared graphics data and moving image coded data to image processing LSI 101 as output data 114.

[0105] The graphics data to be output to image processing LSI 101 are input into CPU 102 as an external input 113.

[0106] Or, these graphics data are generated inside CPU 102 in accordance with information input from external input 113.

[0107] Meanwhile, the MPEG-4 coded data, which are the moving image data to be output to image processing LSI 101, are image coded data input into CPU 102 as external input 113.

[0108] Or, the results of multiplexing image coded data and coded data of sound, etc. are input as external input 113 and the MPEG-4 coded data are the image coded data that have been separated inside CPU 102.

[0109] Control device 110 controls voltage regulating device 111 and power supply interrupting unit 122 so that power supply voltage 127 (power supply voltage VddB) is supplied to the region B that contains image processing unit 104. Control device 110 also controls clock generating device 112 and clock interrupting unit 123 so that clock 131 (clock ClkB) is supplied to the region B that contains image processing unit 104.

[0110] This is because when moving image communication is being performed, a process of decoding the coded data of moving image and a process of synthesizing the decoded moving image data with graphics data, which place the greatest processing load on the system, becomes necessary.

[0111] Control device 110 also controls switch 108 inside bypass unit 105 so that the data 114 output from CPU 102 will be transferred to image processing unit 104.

[0112] Control device 110 also controls selector 109 inside bypass unit 105 so that the processing result data 116 at image processing unit 104 will be output.

[0113] In image processing LSI 101, the graphics data and the coded data, which are the output data 114 from CPU 102, are transferred to image processing unit 104 by switch 108 of bypass unit 105 in accordance with the control by control device 110.

[0114] Upon receiving the graphics data and the coded data, image processing unit 104 performs the decoding process on the coded data.

[0115] After decoding, image processing unit 104 performs the process of synthesizing the decoded moving image data and the graphics data.

[0116] After the synthesizing process has been completed and the display image data have been prepared, image processing unit 104 outputs the display image data 116 to bypass unit 105.

[0117] Bypass unit 105 selects and outputs the received display image data 116 by means of selector 109.

[0118] Display image data 116 are thereby output from image processing LSI 101 to image display device 103 as display image data 118.

[0119] The process is ended by display device 103 displaying the received display image data.

[0120] Next, the operations that are performed when only graphics data output from CPU 102 are to be displayed on display device 103 shall be described.

[0121] First, CPU 102 prepares the graphics data to be displayed on display device 103.

[0122] CPU 102 outputs the prepared graphics data to image processing LSI 101.

[0123] With regard to image data, the output data 114 from CPU 102 to image processing LSI 101 in this case are only graphics data.

[0124] Whether or not the data are only graphics data is notified from CPU 102 to control device 110.

[0125] In the case where only graphics data, such as data for menu display, time display, etc., are to be displayed, the moving image decoding process and the process of synthesizing moving image data with graphics data are unnecessary.

[0126] Control device 110 thus controls voltage regulating device 111 and power supply interrupting unit 122 or controls clock generating device 112 and clock interrupting unit 123 so that either the supplying of power supply voltage 127 (power supply voltage VddB) to region B containing image processing unit 104 or the supplying of clock 131 (clock ClkB) to region B will be stopped.

[0127] Control device 110 also controls switch 108 and selector 109 so that bypass unit 105 will transfer the output data 114 output from CPU 102 directly to display device 103.

[0128] In image processing LSI 101, the graphics data from CPU 102 are output as display image data 118 directly to display device 103 via bypass line 117 of bypass unit 105 in accordance with the control by control device 110.

[0129] The data 118 transferred from image processing LSI 101 to display device 103 correspond to data 314 of FIG. 6.

[0130] The process is ended by display device 103 displaying the received display image data.

[0131] As has been described above, with the first embodiment, image processing unit 104, having the function of decoding MPEG-4 coded data and the function of synthesizing the decoded moving image data with graphics data, is realized, along with a bypass unit 105, by which graphics data can be bypassed around image processing unit 104, on a single LSI.

[0132] Thus in cases where only graphics data are to be displayed, the graphics data can be output to display device 103 via bypass line 117 and an operation equivalent to outputting the graphics data directly to display device 103 from CPU 102 can thus be performed.

[0133] Also in cases where only graphics data are to be displayed, the supplying of power supply voltage 127 (power supply voltage VddB) or the supplying of clock 131 (clock ClkB) to image processing unit 104 can be interrupted.

[0134] This enables wasteful leak currents in image processing unit 104 to be restrained and charging/discharging of the clock line in image processing unit 104 to be restrained.

[0135] Wasteful power consumption, such as power consumption due to leak currents and unnecessary power consumption due to charging/discharging of the clock line, can thus be reduced.

[0136] Also in cases where only graphics data are to be displayed, only region A1, which contains bypass unit 105, in the interior of image processing LSI 101 is made to operate.

[0137] The frequency of clock 130 (clock ClkA) supplied to region A1 can thus be set independent of image processing unit 104 of region B.

[0138] The frequency of clock 130 (clock ClkA) supplied to region A1 can thus be decreased flexibly. Further reduction of power consumption can be achieved by decreasing the clock frequency.

[0139] By the same reason, the level of power supply voltage 126 (power supply voltage VddA) supplied to region A1 can be set independent of image processing unit 104 of region B.

[0140] The level of power supply voltage 126 (power supply voltage VddA) supplied to region A1 can thus be decreased flexibly. Further reduction of power consumption can be achieved by decreasing the voltage level.

[0141] Also by not providing bypass unit 105 on a circuit board onto which the above-described data processing system is mounted but by realizing bypass unit 105 on a single LSI, the mounting area of the system as a whole can be made small.

[0142] That is, bypass unit 105 can be provided without enlarging the area of a circuit board onto which the above-described data processing system is to be mounted.

[0143] Though a case where image processing unit 104 and bypass unit 105 are arranged in a single integrated circuit was described above, these do not have to be arranged in a single integrated circuit.

[0144] Also in the above-described case, when image processing unit 104 does not perform the decoding process on a moving image, one of either the supplying of power supply voltage 127 (power supply voltage VddB) or the supplying of clock 131 (clock ClkB) is interrupted to stop region B.

[0145] However, when image processing unit 104 does not perform the decoding process on a moving image, both the supplying of power supply voltage 127 (power supply voltage VddB) and the supplying of clock 131 (clock ClkB) may be interrupted instead to stop region B.

[0146] Also, though in the above-described case, CPU 102 is the prior-stage data processing unit that outputs data to image processing LSI 101, this data processing unit may instead be a data storage device 190 that stores graphics data and coded data, as shown in FIG. 2.

[0147] Also, though in the above-described case, display device 103 is the subsequent-stage data processing unit that receives data 114 from image processing LSI 101, this data processing unit may instead be a data storage device 191 that stores graphics data and synthesized image data, as shown in FIG. 3.

[0148] Also, CPU 102 was described as a CPU dedicated to image display in the above. However, there may also be cases where CPU 102 performs control of the entire system including image display.

[0149] In such a case, control device 110 controls the stoppage of image processing unit 104, the operation of bypass unit 105, etc. under the control of CPU 102.

[0150] Also, each of CPU 102, region B, and display device 103 may be equipped in plurality in accordance with the data and processing contents.

[0151] (Second Embodiment)

[0152]FIG. 4 is a block diagram, showing the arrangement of a data processing system of a second embodiment of this invention.

[0153] The main point by which the arrangement of this embodiment differs from that of the first embodiment is that a control unit, which performs control of the supplying of power supply voltage and clock to region B and control of bypass unit 105, is arranged in a single integrated circuit.

[0154] Since this embodiment is the same as the first embodiment in points besides the above, the components shown in FIG. 4 that are the same as those of FIG. 1 are provided with the same symbols.

[0155] As shown in FIG. 4, this data processing system is equipped with an image processing LSI 201, a display device 103, a general-purpose processor (CPU) 102, a voltage regulating device 111, a clock generating device 112, a power supply interrupting unit 222, and a clock interrupting unit 223.

[0156] Image processing LSI 201 comprises an image processing unit 104, a bypass unit 105, and a control unit 210. Bypass unit 105 comprises a switch 108, a bypass line 117, and a selector 109.

[0157] The operations of the abovementioned components shall now be described.

[0158] Image processing unit 104 of image processing LSI 201 decodes coded data that have been coded in accordance with the MPEG-4 coding method.

[0159] Image processing unit 104 then synthesizes the decoded moving image with graphics data.

[0160] Bypass unit 105 of image processing LSI 201 is used when graphics data are to be displayed without using image processing unit 104.

[0161] That is, bypass unit 105 outputs graphics data upon bypassing image processing unit 104.

[0162] Display device 103 receives the display image data generated at image processing LSI 201 and displays the received display image data. Display device 103 is, for example, a liquid crystal display, etc.

[0163] CPU 102 prepares graphics data to be displayed on display device 103 and sends the prepared graphics data to image processing LSI 201.

[0164] Also, when a moving image is to be displayed on display device 103, CPU 102 sends the coded data of the moving image to be displayed to image processing LSI 201.

[0165] Voltage regulating device 111 adjusts a voltage generated by a system power supply 124 to appropriate voltages and supplies these appropriate voltages as power supply voltages to image processing LSI 201, CPU 102, and display device 103.

[0166] Clock generating device 112 supplies appropriate clocks to image processing LSI 201, CPU 102, and display device 103.

[0167] CPU 102 operates by a power supply voltage 125, supplied from voltage regulating device 111, and a clock 129, supplied from clock generating device 112.

[0168] Display device 103 operates by a power supply voltage 128, supplied from voltage regulating device 111, and a clock 132, supplied from clock generating device 112.

[0169] Image processing LSI 201 is divided into the two regions of a region A2, which contains bypass unit 105 and control unit 210, and a region B (slanted line part in the Figure), which contains image processing unit 104.

[0170] The region A2, which contains bypass unit 105 and control unit 210, operates by a power supply voltage 126 (power supply voltage VddA), supplied from voltage regulating device 111, and a clock 130 (clock ClkA), supplied from clock generating device 112.

[0171] The region B, which contains image processing unit 104, operates by a power supply voltage 127 (power supply voltage VddB), supplied from voltage regulating device 111, and a clock 131 (clock ClkB), supplied from clock generating device 112.

[0172] Control unit 210 of image processing LSI 201 performs control of the supplying of power supply voltage 127 (power supply voltage VddB) to region B (slanted line part in the Figure) inside image processing LSI 201, control of the supplying of clock 131 (clock ClkB) to region B, and control of bypass unit 105.

[0173] Power supply interrupting unit 222 performs interruption of the power supply voltage in accordance with a control signal 220 from control unit 210.

[0174] Clock interrupting unit 223 performs interruption of the clocks in accordance with a control signal 221 from control unit 210.

[0175] The operations of the respective components of bypass unit 105 shall now be described.

[0176] Bypass line 117 outputs output data 114 from CPU 102 directly to display device 103.

[0177] Switch 108 switches between a path, by which the output data 114 from CPU 102 are output as input data 115 for image processing unit 104, and a path, by which the output data 114 from CPU 102 are output to bypass line 117.

[0178] Selector 109 selects between and outputs either the processing result data 116 at image processing unit 104 or the data output from bypass line 117.

[0179] Switch 108 and selector 109 are controlled by a control signal 219 from control unit 210.

[0180] The data output by bypass unit 105 in accordance with this control signal 219 become the output data 118 of image processing LSI 201.

[0181] The details of the operations of the above-described data processing system shall now be described.

[0182] First, the operations that are performed when the moving image data and graphics data that have been output from CPU 102 are synthesized at image processing LSI 201 and the synthesized image is displayed on display device 103, that is, the image display operations that are performed when moving image communication is carried out shall be described.

[0183] First, CPU 102 prepares the graphics data to be displayed on display device 103 and the moving image coded data that have been coded in accordance with the MPEG-4 coding method.

[0184] CPU 102 then outputs the prepared graphics data and moving image coded data to image processing LSI 201 as output data 114.

[0185] The graphics data to be output to image processing LSI 201 are input into CPU 102 as an external input 113.

[0186] Or, these graphics data are generated inside CPU 102 in accordance with information input from external input 113.

[0187] Meanwhile, the MPEG-4 coded data, which are the moving image data to be output to image processing LSI 201, are image coded data input into CPU 102 as external input 113.

[0188] Or, the results of multiplexing image coded data and coded data of sound, etc. are input as external input 113 and the MPEG-4 coded data are the image coded data that have been separated inside CPU 102.

[0189] Control unit 210 controls voltage regulating device 111 and power supply interrupting unit 222 so that power supply voltage 127 (power supply voltage VddB) is supplied to the region B that contains image processing unit 104. Control unit 210 also controls clock generating device 112 and clock interrupting unit 223 so that clock 131 (clock ClkB) is supplied to the region B that contains image processing unit 104.

[0190] This is because when moving image communication is being performed, a process of decoding the coded data of moving image and a process of synthesizing the decoded moving image data with graphics data, which place the greatest processing load on the system, become necessary.

[0191] Control unit 210 also controls switch 108 inside bypass unit 105 so that the output data 114 output from CPU 102 will be transferred to image processing unit 104.

[0192] Control unit 210 also controls selector 109 inside bypass unit 105 so that the processing result data 116 at image processing unit 104 will be output.

[0193] In image processing LSI 201, the graphics data and the coded data, which are the output data 114 from CPU 102, are transferred to image processing unit 104 by switch 108 of bypass unit 105 in accordance with the control by control unit 210.

[0194] Upon receiving the graphics data and the coded data, image processing unit 104 performs the decoding process on the coded data.

[0195] After decoding, image processing unit 104 performs the process of synthesizing the decoded moving image data and the graphics data.

[0196] After the synthesizing process has been completed and the display image data have been prepared, image processing unit 104 outputs the display image data 116 to bypass unit 105.

[0197] Bypass unit 105 selects and outputs the received display image data 116 by means of selector 109.

[0198] Display image data 116 are thereby output from image processing LSI 201 to image display device 103 as display image data 118.

[0199] The process is ended by display device 103 displaying the received display image data 118.

[0200] Next, the operations that are performed when only graphics data output from CPU 102 are to be displayed by display device 103 shall be described.

[0201] First, CPU 102 prepares the graphics data to be displayed on display device 103.

[0202] CPU 102 outputs the prepared graphics data to image processing LSI 201.

[0203] With regard to image data, the output data 114 from CPU 102 to image processing LSI 201 in this case are only graphics data.

[0204] Whether or not the data are only graphics data is notified from CPU 102 to control unit 210.

[0205] In the case where only graphics data, such as data for menu display, time display, etc., are to be displayed, the moving image decoding process and the process of synthesizing moving image data with graphics data are unnecessary.

[0206] Control unit 210 thus controls voltage regulating device 111 and power supply interrupting unit 222 or controls clock generating device 112 and clock interrupting unit 223 so that either the supplying of power supply voltage 127 (power supply voltage VddB) to region B containing image processing unit 104 or the supplying of clock 131 (clock ClkB) to region B will be stopped.

[0207] Control unit 210 also controls switch 108 and selector 109 so that bypass unit 105 will transfer the output data 114 output from CPU 102 directly to display device 103.

[0208] In image processing LSI 201, the graphics data from CPU 102 are output as display image data 118 directly to display device 103 via bypass line 117 of bypass unit 105 in accordance with the control by control unit 210.

[0209] The data 118 transferred from image processing LSI 201 to display device 103 correspond to data 314 of FIG. 6.

[0210] The process is ended by display device 103 displaying the received display image data.

[0211] As has been described above, with the second embodiment, image processing unit 104, having the function of decoding MPEG-4 coded data and the function of synthesizing the decoded moving image data with graphics data, is realized, along with bypass unit 105, by which graphics data can be bypassed around image processing unit 104, and control unit 210, on a single LSI.

[0212] Thus in cases where only graphics data are to be displayed, the graphics data can be output to display device 103 via bypass line 117 and an operation equivalent to outputting the graphics data directly to display device 103 from CPU 102 can thus be performed.

[0213] Also in cases where only graphics data are to be displayed, the supplying of power supply voltage 127 (power supply voltage VddB) or the supplying of clock 131 (clock ClkB) to image processing unit 104 can be interrupted.

[0214] This enables wasteful leak currents in image processing unit 104 to be restrained and charging/discharging of the clock line in image processing unit 104 to be restrained.

[0215] Wasteful power consumption, such as power consumption due to leak currents and unnecessary power consumption due to charging/discharging of the clock line, can thus be reduced.

[0216] Also in cases where only graphics data are to be displayed, only region A2, which contains bypass unit 105, in the interior of image processing LSI 201 is made to operate.

[0217] The frequency of clock 130 (clock ClkA) supplied to region A2 can thus be set independent of image processing unit 104 of region B.

[0218] The frequency of clock 130 (clock ClkA) supplied to region A2 can thus be decreased flexibly. Further reduction of power consumption can be achieved by decreasing the clock frequency.

[0219] By the same reason, the level of power supply voltage 126 (power supply voltage VddA) supplied to region A2 can be set independent of image processing unit 104 of region B.

[0220] The level of power supply voltage 126 (power supply voltage VddA) supplied to region A2 can thus be decreased flexibly. Further reduction of power consumption can be achieved by decreasing the voltage level.

[0221] Also by realizing bypass unit 105 and control unit 210 on a single LSI, the mounting area of the system as a whole can be made even smaller than in the first embodiment.

[0222] Also in the above-described case, when image processing unit 104 does not perform the decoding process on a moving image, one of either the supplying of power supply voltage 127 (power supply voltage VddB) or the supplying of clock 131 (clock ClkB) is interrupted to stop region B.

[0223] However, when image processing unit 104 does not perform the decoding process on a moving image, both the supplying of power supply voltage 127 (power supply voltage VddB) and the supplying of clock 131 (clock ClkB) may be interrupted instead to stop region B.

[0224] Also, though in the above-described case, CPU 102 is the prior-stage data processing unit that outputs data 114 to image processing LSI 201, the data storage device 190 of FIG. 2 may be provided in place of this CPU 102.

[0225] Also, though in the above-described case, display device 103 is the subsequent-stage data processing unit that receives data 118 from image processing LSI 201, the data storage device 191 of FIG. 3 may be provided in place of this display device 103.

[0226] Also, CPU 102 was described as a CPU dedicated to image display in the above. However, there may also be cases where CPU 102 performs control of the entire system including image display.

[0227] In such a case, control unit 210 controls the stoppage of image processing unit 104, the operation of bypass unit 105, etc. under the control of CPU 102.

[0228] Also, each of CPU 102, region B, and display device 103 may be equipped in plurality in accordance with the data and processing contents.

[0229] (Third Embodiment)

[0230]FIG. 5 is a block diagram, showing the arrangement of a data processing system of a third embodiment of this invention. In FIG. 5, the parts that are the same as those of FIG. 1 are provided with the same symbols and descriptions thereof shall be omitted where suitable.

[0231] As shown in FIG. 5, this data processing system is equipped with an image processing LSI 501, a display device 103, a general-purpose processor (CPU) 102, a voltage regulating device 111, a clock generating device 112, a control device 110, a power supply interrupting unit 122, a clock interrupting unit 123, and a bypass circuit 505.

[0232] Image processing LSI 501 comprises an image processing unit 104.

[0233] Bypass circuit 505 comprises a switch 508, a bypass line 517, and a selector 509.

[0234] The operations of the abovementioned respective components shall now be described, mainly in regard to the points of difference with respect to the first embodiment.

[0235] Bypass circuit 505 is used when graphics data are to be displayed without using image processing unit 104.

[0236] That is, bypass circuit 505 outputs graphics data upon bypassing image processing unit 104.

[0237] Voltage regulating device 111 adjusts a voltage generated by a system power supply 124 to appropriate voltages and supplies these appropriate voltages as power supply voltages to image processing LSI 501, CPU 102, display device 103, and bypass circuit 505.

[0238] Clock generating device 112 supplies appropriate clocks to image processing LSI 501, CPU 102, display device 103, and bypass circuit 505.

[0239] Image processing LSI 501, which contains image processing unit 104, operates by a power supply voltage 127 (power supply voltage VddB), supplied from voltage regulating device 111, and a clock 131 (clock ClkB), supplied from clock generating device 112.

[0240] Bypass circuit 505 operates by a power supply voltage 126 (power supply voltage VddA), supplied from voltage regulating device 111, and a clock 130 (clock ClkA), supplied from clock generating device 112.

[0241] Control device 110 performs control of the supplying of power supply voltage 127 (power supply voltage VddB) to image processing LSI 501, control of the supplying of clock 131 (clock ClkB) to image processing LSI 501, and control of bypass circuit 505.

[0242] The operations of the respective components of bypass circuit 505 shall now be described.

[0243] Bypass line 517 outputs output data 114 from CPU 102 directly to display device 103.

[0244] Switch 508 switches between a path, by which the output data 114 from CPU 102 are output as input data 115 for image processing unit 104, and a path, by which the output data 114 from CPU 102 are output to bypass line 517.

[0245] Selector 509 selects between and outputs either the processing result data 116 at image processing unit 104 or the data output from bypass line 517.

[0246] Switch 508 and selector 509 are controlled by a control signal 119 from control device 110.

[0247] The data output by bypass circuit 505 in accordance with this control signal 119 become the input data 118 for display device 103.

[0248] The details of the operations of the above-described data processing system shall now be described.

[0249] First, the operations that are performed when the moving image data and graphics data that have been output from CPU 102 are synthesized at image processing LSI 501 and the synthesized image is displayed on display device 103, that is, the image display operations that are performed when moving image communication is carried out shall be described.

[0250] First, CPU 102 prepares the graphics data to be displayed on display device 103 and the moving image coded data that have been coded in accordance with the MPEG-4 coding method.

[0251] CPU 102 then outputs the prepared graphics data and moving image coded data to bypass circuit 505 as output data 114.

[0252] Control device 110 controls voltage regulating device 111 and power supply interrupting unit 122 so that power supply voltage 127 (power supply voltage VddB) is supplied to image processing LSI 501 that contains image processing unit 104. Control device 110 also controls clock generating device 112 and clock interrupting unit 123 so that clock 131 (clock ClkB) is supplied to image processing LSI 501 that contains image processing unit 104.

[0253] Control device 110 also controls switch 508 inside bypass circuit 505 so that the output data 114 output from CPU 102 will be transferred to image processing unit 104.

[0254] Control device 110 also controls selector 509 inside bypass circuit 505 so that the processing result data 116 at image processing unit 104 will be output.

[0255] The graphics data and the coded data, which are the output data 114 from CPU 102, are transferred to image processing unit 104 by switch 508 of bypass circuit 505 in accordance with the control by control device 110.

[0256] Upon receiving the graphics data and the coded data, image processing unit 104 performs a decoding process on the coded data.

[0257] After decoding, image processing unit 104 performs a process of synthesizing the decoded moving image data and the graphics data.

[0258] After the synthesizing process has been completed and the display image data have been prepared, image processing unit 104 outputs the display image data 116 to bypass circuit 505.

[0259] Bypass circuit 505 selects and outputs the received display image data 116 by means of selector 509.

[0260] Display image data 116 are thereby output from image processing LSI 501 to image display device 103 as display image data 118.

[0261] The process is ended by display device 103 displaying the received display image data 116.

[0262] Next, the operations that are performed when only graphics data output from CPU 102 are to be displayed on display device 103 shall be described.

[0263] First, CPU 102 prepares the graphics data to be displayed on display device 103.

[0264] CPU 102 outputs the prepared graphics data to bypass circuit 505.

[0265] With regard to image data, the output data 114 from CPU 102 to bypass circuit 505 in this case are only graphics data.

[0266] Whether or not the data are only graphics data is notified from CPU 102 to control device 110.

[0267] In the case where only graphics data, such as data for menu display, time display, etc., are to be displayed, the moving image decoding process and the process of synthesizing moving image data with graphics data are unnecessary.

[0268] Control device 110 thus controls voltage regulating device 111 and power supply interrupting unit 122 or controls clock generating device 112 and clock interrupting unit 123 so that either the supplying of power supply voltage 127 (power supply voltage VddB) to image processing LSI 501, which contains image processing unit 104, or the supplying of clock 131 (clock ClkB) to image processing LSI 501 will be stopped.

[0269] Control device 110 also controls switch 508 and selector 509 so that bypass circuit 505 will transfer the output data 114 output from CPU 102 directly to display device 103.

[0270] The graphics data from CPU 102 are thus output as display image data 118 directly to display device 103 via bypass line 517 of bypass circuit 505 in accordance with the control by control device 110.

[0271] The data 118 transferred from bypass circuit 505 to display device 103 correspond to data 314 of FIG. 6.

[0272] The process is ended by display device 103 displaying the received display image data 118.

[0273] As has been described above, with the third embodiment, image processing unit 104, having the function of decoding MPEG-4 coded data and the function of synthesizing the decoded moving image data with graphics data, is provided along with a bypass circuit 505, by which graphics data can be bypassed around image processing unit 104.

[0274] Thus in cases where only graphics data are to be displayed, the graphics data can be output to display device 103 via bypass line 517 and an operation equivalent to outputting the graphics data directly to display device 103 from CPU 102 can thus be performed.

[0275] Also in cases where only graphics data are to be displayed, the supplying of power supply voltage 127 (power supply voltage VddB) or the supplying of clock 131 (clock ClkB) to image processing unit 104 can be interrupted.

[0276] This enables wasteful leak currents in image processing unit 104 to be restrained and charging/discharging of the clock line in image processing unit 104 to be restrained.

[0277] Wasteful power consumption, such as power consumption due to leak currents and unnecessary power consumption due to charging/discharging of the clock line, can thus be reduced.

[0278] Since clock 130 (clock ClkA) and clock 131 (clock ClkB) are generated separately, the frequency of clock 130 (clock ClkA) supplied to bypass circuit 505 can be decreased flexibly. Further reduction of power consumption can be achieved by decreasing the clock frequency.

[0279] Also since power supply voltage 126 (power supply voltage VddA) and power supply voltage 127 (power supply voltage VddB) are generated separately, the level of power supply voltage 126 (power supply voltage VddA) supplied to bypass circuit 505 can be decreased flexibly. Further reduction of power consumption can be achieved by decreasing the voltage level.

[0280] Also in the above-described case, when image processing unit 104 does not perform the decoding process on a moving image, one of either the supplying of power supply voltage 127 (power supply voltage VddB) or the supplying of clock 131 (clock ClkB) is interrupted to stop image processing LSI 501.

[0281] However, when image processing unit 104 does not perform the decoding process on a moving image, both the supplying of power supply voltage 127 (power supply voltage VddB) and the supplying of clock 131 (clock ClkB) may be interrupted instead to stop image processing LSI 501.

[0282] Also, though in the above-described case, CPU 102 is the prior-stage data processing unit that outputs data 114 to bypass circuit 505, the data storage device 190 of FIG. 2 may be provided in place of this CPU 102.

[0283] Also, though in the above-described case, display device 103 is the subsequent-stage data processing unit that receives data 118 from bypass circuit 505, the data storage device 191 of FIG. 3 may be provided in place of this display device 103.

[0284] Also, CPU 102 was described as a CPU dedicated to image display in the above. However, there may also be cases where CPU 102 performs control of the entire system including image display.

[0285] In such a case, control device 110 controls the stoppage of image processing unit 104, the operation of bypass circuit 505, etc. under the control of CPU 102.

[0286] Also, each of CPU 102, image processing LSI 501, and display device 103 may be equipped in plurality in accordance with the data and processing contents.

[0287] Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims. 

What is claimed is:
 1. A data processing system comprising: at least one first data processing unit operable to perform preprocessing and output preprocessed data; at least one second data processing unit operable to perform data processing on the preprocessed data and output processing result data; at least one third data processing unit operable to perform postprocessing on the processing result data; a bypass unit operable to transfer the preprocessed data from said first data processing unit to one of said second data processing unit and said third data processing unit; and a control unit operable to control said bypass unit; wherein said bypass unit is operable to, in a case where processing of the preprocessed data by said second data processing unit is not required, transfer the input preprocessed data to said third data processing unit in accordance with an instruction from said control unit, and wherein said control unit is operable to, in a case where processing of the preprocessed data by said second data processing unit is not required, stop data processing by said second data processing unit.
 2. The data processing system as set forth in claim 1, wherein said second data processing unit and said bypass unit are arranged within a single integrated circuit.
 3. The data processing system as set forth in claim 1, wherein said second data processing unit, said bypass unit, and said control unit are arranged within a single integrated circuit.
 4. The data processing system as set forth in claim 1, wherein said control unit is operable to stop supply of a clock signal to said second data processing unit to stop data processing by said second data processing unit.
 5. The data processing system as set forth in claim 1, wherein said control unit is operable to stop supply of power supply voltage to said second data processing unit to stop data processing by said second data processing unit.
 6. The data processing system as set forth in claim 1, wherein said control unit is operable to stop supply of a clock signal and supply of power supply voltage to said second data processing unit to stop data processing by said second data processing unit.
 7. The data processing system as set forth in claim 1, wherein said first data processing unit comprises a processor.
 8. The data processing system as set forth in claim 1, wherein said first data processing unit comprises a data storage device.
 9. The data processing system as set forth in claim 1, wherein said third data processing unit comprises a display device.
 10. The data processing system as set forth in claim 1, wherein said third data processing unit comprises a data storage device.
 11. A data processing system comprising: a bypass unit operable to output input data to either a first path or a second path; and at least one data processing unit operable to perform data processing on the data output to said second path and output processing result data; wherein said bypass unit is operable to, in a case where the input data are not required to be processed by said data processing unit, output the input data to said first path, which is not connected to said at least one data processing unit, and said data processing unit is operable to, in a case where the input data of said bypass unit are not required to be processed by said data processing unit, stop data processing.
 12. The data processing system as set forth in claim 11, wherein said data processing unit and said bypass unit are arranged within a single integrated circuit.
 13. A data processing system comprising: a bypass unit operable to output input data to either a first path or a second path; a control unit operable to control said bypass unit; and at least one data processing unit operable to perform data processing on the data output to said second path and output processing result data; wherein said bypass unit is operable to, in a case where the input data are not required to be processed by said data processing unit, output the input data to said first path, which is not connected to said data processing unit, in accordance with an instruction of said control unit, and said unit is operable to, in a case where the input data of said bypass unit are not required to be processed by said data processing unit, stop data processing by said data processing unit.
 14. The data processing system as set forth in claim 13, wherein said data processing unit, said bypass unit, and said control unit are arranged within a single integrated circuit.
 15. The data processing system as set forth in claim 13, wherein said control unit is operable to stop supply of a clock signal to said data processing unit to stop data processing by said data processing unit.
 16. The data processing system as set forth in claim 13, wherein said control unit is operable to stop supply of power supply voltage to said data processing unit to stop data processing by said data processing unit.
 17. The data processing system as set forth in claim 13, wherein said control unit is operable to stop supply of a clock signal and supply of a power supply voltage to said data processing unit to stop data processing by said data processing unit. 